When you say “log-structured file system,” most storage developers will immediately think of Ousterhout and Rosenblum’s classic paper, The Design and Implementation of a Log-structured File System - and the nearly two decades of subsequent work attempting to solve the nasty segment cleaner problem (see below) that came with it. Linux developers might think of JFFS2, NILFS, or LogFS, three of several modern log-structured file systems specialized for use with solid state devices (SSDs). Few people, however, will think of SSD firmware. The flash translation layer in a modern, full-featured SSD resembles a log-structured file system in several important ways. Extrapolating from log-structured file systems research lets us predict how to get the best performance out of an SSD. In particular, full support for the TRIM command, at both the SSD and file system levels, will be key for sustaining long-term peak performance for most SSDs.